D5.9: Extended Simulation Environment - Phosphorus

D5.6 - Extended Simulation Environment
3.1.6 Residual Network
The residual network for a new anycasting request is built with nodes with sufficient resources (e.g. memory,
processor, etc.) and links with a residual capacity exceeding the request bandwidth requirement. Bandwidth
requirements of both upstream and downstream routes are considered, and as such only reachable servers
with enough resources are taken into account in the selection. Such servers are called available servers.
3.1.7 Results
The connection blocking probability is used as the comparison metric. The blocking probability is calculated for
each class individually as the ratio of the number of blocked requests of that class to the total number of
requests of that class. An anycast request is considered to be blocked if no available servers are found. Also
Class 1 and Class 2 anycasting requests are blocked if either the upstream or downstream connections of the
paths to the primary or the backup servers cannot be established. An anycast request of Class 3 is blocked if
either the upstream or downstream connections of the path to the primary server cannot be established. The
obtained results are averaged out over various cases of server locations. Results are collected in a specially
defined structure and stored in an easily processed form.
3.1.8 Traffic Generator
The traffic of each node is simply generated prior to the start of the simulation and stored in a file. When a
simulation is started, a function called read_anycasting_request() is used to fetch the traffic from the files into
the nodes.
For the simulation scenario, we assume the total traffic consists of 10% Class 1, 30% Class 2, and 60% Class
3. As the anycast flow is asymmetrical, bandwidth requirements are assumed to be as follows: The upstream
connections of all traffic classes are assumed to be 1 bandwidth unit. The downstream connections
requirements are assumed to be uniformly distributed in the range of (4-10) units for Class 1 and Class 2.
Requirements of Class 3 are assumed to be uniformly distributed in the range of (0-4) units. The values of
these parameters can be easily changed to run the simulator under a different traffic scenario.
3.1.9 Routing and Server Selection Algorithms
The user can choose to run the simulator under any combination of the server selection algorithms (HNS, RCS
and HNSW) and the routing algorithms (CSPF and LIOA) by executing the select_server() and
routing_algorithm() functions.
Project:
Phosphorus
Deliverable Number:
Date of Issue: 2009-03-31
EC Contract No.: 034115
Document Code:
16